Process for coloring polytrimethylene terephthalate fibres and use of the fibres colored by this process

ABSTRACT

The present invention relates to a process for coloring polytrimethylene terephthalate fibers by treating the fibers with an aqueous liquor containing at least one dispersing colorant, in the absence of a carrier and the application of pressure. The temperature of the treatment is carried out at or below the boiling point of the liquid, within 20° C. of the boiling point of the liquor. The coloring process begins at a liquor temperature between 20° and 50° C., and the temperature is raised over a period of 20 to 90 minutes. The liquor is then cooled to a temperature between 20° and 50° C., preferably at a rate of cooling of 1° C. per minute, so that at least 95% wt. % of the colorant is absorbed by the fibers, and the dispersing colorant penetrates the fibers to a relative depth of at least 5% with respect to the diameter of the fibers.

BACKGROUND OF THE INVENTION

The invention relates to a process for colouring polytrimethyleneterephthalate fibrrs using disperse colorants in aqueous liquors at orbelow the boiling point of the liquor and use of the fibres colouredaccording to the invention.

BACKGROUND

Polytrimethylene terephthalate (PTMT) is a polyester which has1,3-propanediol as the diol component and terephthalic acid as thedicarboxylic acid component. Large-scale synthesis of polyesters maybasically be performed by two different methods (H-D. Schumann inChemiefasern/Textilind. 40/92 (1990), p. 1058 et seq.).

On the one hand, the older process, which was exclusively used up toabout 1960, involving transesterification of dimethyl terephthalate witha diol to give bis-hydroxyalkyl terephthalate and subsequentpolycondensation. On the other hand, the method extensively used today,involving direct esterification of terephthalic acid with a diol andsubsequent polycondensation.

During transesterification, dimethyl terephthalate is transesterifiedwith 1,3-propanediol using catalysts at temperatures of 160°-210° C. andthe methanol being released is distilled out of the reaction mixture atatmospheric pressure. The reaction mixture, which comprises mostlybis-(3-hydroxypropyl) terepthalate, is further heated to 250°-280° C.under reduced pressure and the 1,3-propanediol being released isremoved. Formation of polytrimethylene terephthalate frombis-(3-hydroxylpropyl) terephthalate may be catalysed by the samecatalyst as used for transesterification or, after deactivation of thesame, a different polycondensation catalyst may be added. ##STR1##

The preparation of polytrimethylene terephthalate has already beendescribed in GB 578079. Transesterification of dimethyl terephthalatewith 1,3-propanediol is catalysed by sodium and magnesium. The alcoholsreleased are distilled off at atmospheric pressure and the reactionmixture is further heated under reduced pressure until polymericpolytrimethylene terephthalate is obtained.

A compound fibre made from polyethylene terephthalate andpolytrimethylene terephthalate is described in GB 1075689. Whenpreparing the polytrimethylene terephthalate, dimethyl terephthalate and1,3-propane diol are used as starting materials and titaniumtetrabutylate is used as transesterification and polycondensationcatalyst.

Two catalyst systems for preparing polytrimethylene terephthalate areknown from FR 2038039. In both cases, dimethyl terephthalate and1,3-propanediol are used as starting materials. On the one hand, NaHTi(OBu)₆ ! is used as transesterification and polycondensation catalystand in the other process "Tyzor TBT" from Du Pont and MgCO₃ are used astransesterification catalysts and an antimony compound is used as thepolycondensation catalyst.

German document OS 19 54 527 relating to catalysts for preparingpolyesters, describes another possibility for catalysis during theproduction of polytrimethylene terephthalate. Here again, dimethylterephthalate and 1,3-propanediol are used as starting materials.

Manganese(II) acetate tetrahydrate is used as the transesterificationcatalyst and hexagonal crystalline germanium dioxide with a particlesize of less than 2 μm is used as the polycondensation catalyst. Thesecatalysts may also be used for producing dipolymers from terephthalicacid, 1,2-ethanediol and 1,3-propanediol.

A further catalyst mixture which is not based on titanium is describedin U.S. Pat. No. 4,167,541. In this case cobalt acetate and zinc acetateare described as catalysts for the transesterification of dimethylterephthalate using 1,3-propanediol and antimony oxide is used as thecatalyst for polycondensation.

A new type of catalyst system is described in U.S. Pat. No. 4,611,049and DE-OS 34 22 733. Again starting from dimethyl terephthalate and1,3-propanediol, titanium tetrabutylate is added as catalyst. Inaddition, p-toluenesulphonic acid is added as promoter, thus achieving ahigher molecular weight.

In 1988, C. C. Gonzalez, J. M. Perena and A. Bello (J. Polym. Sci., PartB: Polymer Physics 26 (1988), 1397) prepared linear polyesters startingfrom dimethyl terephthalate, 1,3-propanediol and ditrimethylene glycol.Tetraisopropyl titanate is used as transesterification andpolycondensation catalyst. Copolymers of terephthalic acid,1,3-propanediol and ditrimethylene glycol can also be prepared usingthis same catalyst.

Various further catalyst systems have been described only recently, inEP 0 547 553. Starting from dimethyl terephthalate and 1,3-propanediol,titanium tetrabutylate, sodium and titanium tetrabutylate, zinc acetate,cobalt acetate and titanium tetrabutylate, as well as butylhydroxytinoxide have been described as transesterification catalysts. Thepolycondensation catalysts used are titanium tetrabutylate, antimonytrioxide, butylhydroxytin oxide and a combination of antimony trioxideand butylhydroxytin oxide.

This also gives, for the first time, a synthesis pathway for directesterification. Starting from terephthalic acid and 1,3-propanediol,esterification is performed thermally under pressure and the subsequentpolycondensation is catalysed by antimony trioxide.

All the publications listed above described different ways for makingPTMT or fibres therefrom. None of the publications, however, discloseany technical details relating to colouring PTMT fibres.

With regard to other polyester fibres, e.g. polyethylene terephthalatefibres, there is already a whole set of investigations regarding theircolouring behaviour. Thus, it is known (Herlinger, Gutmann and Jiang inCTI, Chemiefasern/Textilindustrie 37/89, February 1987, p. 144-150),that the use of polyethylene terephthalate in the textile sector isalways associated with certain problems with respect to colouring.

SUMMARY OF THE INVENTION

Basically polyesters can only be optimally coloured with dispersecolorants using carriers under so-called HT conditions, i.e. at elevatedtemperature, eg. 130° C., in pressurised vessels (Bela v. Falkai in"Synthesefasern", Verlag Chemie, Weinheim, 1981, p. 176). Carriers arespecial auxiliary agents which have to be added to the colorant liquorsin order first of all to enable absorption of the colorant in practice.Examples of carriers, which may also be called fibre swelling agents,are, inter alia, o-hydroxybiphenyl or trichlorobenzene. It is assumedthat this type of auxiliary agent lowers the freezing temperature abovewhich the large molecular segments of the fibres in the non-crystallineareas become mobile, which accelerates the colouring process.

The necessity for removing the carrier from the fibre after thecolouring procedure, in order to avoid it having an unfavourable effecton the serviceability of the fibres, concern about environmentalprotection (pollution of effluents and the air by carriers) and problemswith colouring polyester/wool mixtures (wool cannot be coloured in a HTprocess) led to the development of polyester fibres which can becoloured at boiling point without the use of a carrier.

In order to produce polyesters which can be coloured without a carrierat boiling point and without applying a pressure, it is known that thepolyester can be chemically or physically modified (Herlinger et al. in:Chemiefaser/Textilindustrie CTI 37/89, p. 144-150, inChemiefaser/Textilindustrie CTI 37/89, p. 806-814 and inChemiefaser/Textilindustrie CTI 40/92, Feb. 1990).

In the case of chemical modification, for example, ether-modifiedpolyethylene terephthalate was prepared. Thus, during the production ofpolyethylene terephthalate polymer (PETP), polyether blocks, consistingof polyethylene glycol (PEG) units were incorporated into the PETPchains, these facilitating the absorption of colorants due to theirmobility. Similarly, it was attempted to incorporate by polymerisationinto the polyethylene terephthalate, polybutylene glycol units insteadof the PEG units. A lowering of the glass transition temperature is alsonoted with this type of polyester and the colouring behaviour isdefinitely improved.

Furthermore, it is known that copolyesters of polyethylene terephthalateand polybutylene terephthalate may be prepared to improve the colouringproperties, but these do not have sufficient thermal stability, so theycannot be considered as an alternative, like pure polybutyleneterephthalate, which basically can also be coloured without using acarrier but has too low a melting point, which does not permitapplication of the elevated temperatures required for the finishingsteps.

In contrast good thermal stability is exhibited by physically modifiedtypes of polyethylene terephthalate which have been produced by thecoextrusion of mechanical mixtures of polyethylene terephthalate andpolybutylene terephthalate granules.

It is known, from DE 36 43 752 A1, that fibres of polybutyleneterephthalate can be coloured with disperse colorants in aqueous liquorswithout the use of carriers and without the application of pressure.

It is known from Ullmann, 4th ed., vol. 22, p. 678 (1983) that in thecase of PET very pale shades of colours may sometimes be produced, bycolouring without the use of carriers or of pressure. The type ofdisperse colorants which are suitable for this are those which candiffuse rapidly enough into the PET fibres at 100° C., e.g. C. I.disperse red 60. Using this procedure, however, as already mentionedabove, at the very best weak annular colouring of the fibre surface isproduced, wherein generally only an extremely small proportion of thecolour present in the liquor is absorbed. The results in every case arepale shades of colour with a low colour intensity. This is true ingeneral terms for all disperse colorants, even for those which have ahigh coefficient of diffusion.

Finally, U.S. Pat. No. 3,841,831 discloses a colouring process forpolyester fibres in which the colouring is performed without a carrierand without pressure, using disperse colorants in an aqueous bath at 25°to 100° C. This general statement, however, is severely restricted inthe description of U.S. Pat. No. 3,841,831, in fact on the one hand toPET fibres and on the other hand to extremely small amounts of colorantin the colouring bath. In addition, the cited colouring process alwaysincludes an additional fixing step in order to facilitate somewhatdeeper penetration of the colorant into the fibres. All this supportsthe fact that when using PET in the textile sector, optimal colouringwithout the use of a carrier or of pressure, has hitherto not beenpossible.

Basically it should be noted that most of the polyester productshitherto disclosed which can be coloured without the use of a carrier,at boiling point and without the application of pressure, barelycorrespond to the picture which the consumer associates with knownpolyester fibres. In some the initial modulus of elasticity is reduced(they feel limp), there is a greater tendency to crease, the resistanceto washing suffers, the ability to recover their shape decreases or thetendency to pill increases.

In view of the prior art described above, the object of the inventionwas to provide a process for colouring polytrimethylene terephthalatefibres which could be used for environmentally friendly permanentcolouring of polytrimethylene terephthalate fibres and in addition whichleads to coloured polyester fibres which have outstanding processingproperties and which also satisfy the current demands placed onpolyester fibres from a thermal and mechanical point of view. Inparticular, the colour in the coloured fibres should have increasedwear-resistance when the fibres and textile products produced therefromare used, in cases where the wear is due to repeated abrasion at thefibre surface.

This, and other objects which are not stated in detail, is achieved by aprocess with the features in the description below.

When polytrimethylene terephthalate fibres (PTMT fibres) are treatedwith an aqueous liquor which contains at least one disperse colorant,wherein the temperature is at or below the boiling point of the liquor,no carrier is added and pressure is not applied, wherein at the sametime the colouring process is started at a liquor temperature between20° and 50° C., the temperature is raised over 20-90 minutes, preferablyover 45 minutes, to the boiling point of the liquor or to a colouringtemperature which is a maximum of 20° C. below the boiling point of theliquor, colouring is continued for at least 20 minutes, preferably 30-90minutes, at the colouring temperature or boiling point and then theliquor is cooled to a temperature of 20°-50° C., preferably at a rate ofcooling of 1° C. per minute, so that at least 95 wt. % of the colorantpresent in the liquor is absorbed by the PTMT fibres, and the dispersecolorant penetrates the fibres to a relative depth of at least 5% withrespect to the diameter of the fibres being coloured, this enablesenvironmentally friendly colouring of the PTMT fibres and the productionof coloured PTMT fibres with outstanding colorant properties and withexceptional mechanical and thermal properties, which can be furtherprocessed very advantageously to produce woven and knitted fabrics ofall types.

Within the context of the invention, it has been demonstrated thatbasically all known polytrimethylene terephthalate fibres can becoloured with disperse colorants without using a carrier. In particular,this also includes the fibres obtainable in accordance with the processdisclosed in EP 0 547 533.

This was rather surprising because, starting from the experiencesavailable with regard to polyethylene terephthalate, the favourablecolouring behaviour of polytrimethylene terephthalate would not havebeen expected.

Even if account is taken of the fact that it is known that polyesters ofpure polybutylene glycol terephthalate can be coloured without the useof carriers, this could not be assumed from the outset to be the casefor fibres made from polytrimethylene terephthalate. Apart from thecolouring properties, there are also, inter alia, thermal properties ofthe polyester which have to be considered in relation to serviceability.In the case of a polymer which is suitable as a raw material for fibresfor textile purposes, the melting point of the basic ester should bewell above 200° C. The melting points of esters from diols with an oddnumber of methylene groups in the diol, however, are generally below themelting points of the esters with the next highest even number ofmethylene groups in the diol. This effect, however, is only clearlydemonstrated with higher numbers of methylene groups. In the case ofpolytrimethylene and polybutylene terephthalate, the melting points arealmost identical.

Also, with respect to the glass transition temperature, which should beas low as possible for good colouring properties at boiling pointwithout adding a carrier, the prior art did not give a clear pointer tothe suitability of polytrimethylene terephthalate for being colouredwithout the use of a carrier. The information provided by variousauthors differs greatly. G. Farrow et al. in Makromol. Chem. 38 (1960)p. 147 established the glass transition temperature at 95° C., and thusabove that of polybutylene terephthalate, whereas a glass transitiontemperature of 45° C. is cited for polytrimethylene terephthalate inU.S. Pat. No. 3,681,188. Jackson et al. in J. Appl. Polym. Sci. 14(1970), p. 685, also publish a glass transition temperature forpolytrimethylene terephthalate which is above that of polybutyleneterephthalate. All in all, therefore, starting from the existingphysical data with regard to colouring behaviour, no unambiguousconclusion can be drawn from the outset as to the similarity topolybutylene terephthalate or to polyethylene terephthalate.

According to the invention, polytrimethylene terephthalate fibres areparticularly preferably coloured which are obtainable frompolytrimethylene terephthalate which has been produced by using a singlecatalyst, preferably a titanium compound, for transesterification andfor subsequent polycondensation. In this case, it is of particularadvantage that the transesterification catalyst is not converted into aninactive form prior to polycondensation. Furthermore, the catalyticallyactive species in many cases is produced only in the reaction mixtureand it can remain in the polymer until reaction has terminated.

Fibres for the invention made of the PTMT material obtained can beproduced by any method commonly used by a person skilled in the art. Thepolytrimethylene terephthalate is preferably subjected to a meltspinning process to produce the fibres, wherein the polymer material isfirst dried to a water content of less than 0.02 wt. %, preferably attemperatures of about 165° C. The polyester spun fibres obtained may, ifso desired, be hot stretched at temperatures of 110° C. (hot pin) or 90°C. (heating block) before being coloured, using a stretching systemknown to a person skilled in the art.

The disperse colorants (disperse dyes) which can be used in the processaccording to the invention are not restricted to specific compounds butrather include all colorants with low solubility in water which arecapable of colouring hydrophobic fibres from an aqueous dispersion.Suitable disperse colorants are familiar to a person skilled in the artand examples which may be mentioned are colorant classes from the azoseries, aminoanthraquinones or aminohydroxyanthaquinones or nitrocolorants. Included among these are monoazo colorants which have severalnitro or cyano substituents and heterocyclic azo and polymethinecolorants. Members of these colorant classes may be used singly or inmixtures of several together, wherein members of different classes maybe mixed with each other to produce, for example, shades of green orblack. Furthermore, it is possible, in the context of the invention, toconsider colorants for colouring processes which are basically used forcolouring cotton, wherein a diaminoazo compound is applied as a colorantusing the disperse method, diazotised on the fibre and reacted with asuitable coupling compound to produce trisazo black substances.Furthermore, the invention also covers all variants of so-called finishcolouring for disperse colorants.

At the beginning of the invention, the disperse colorants are present inan aqueous liquor. During the colouring procedure they are distributedbetween the aqueous liquor and the fibre being treated therewith in thesame way as between two immiscible or barely miscible liquids and arethen absorbed onto the fibres by means of appropriate reaction controlprocedures and selection of substances.

The fibres are treated in the process according to the inventionessentially by placing the fibres and liquor in contact (in an aqueoussolution containing the disperse colorants and any auxiliary agentsrequired), for example by immersing the fibres in the liquor and leavingthem there for a period. This process is performed, according to theinvention, without the addition of carriers and without the applicationof pressure, i.e. without applying pressures greater than atmosphericpressure, at the boiling point of the liquor or at a temperature belowthe boiling point of the liquor, in fact so that at least 95% of thecolorant present in the liquor is absorbed onto the PTMT fibres. Thisgenerally corresponds to a colouring process which exhausts the bath,i.e. the colorant present is completely taken up by the fibres beingtreated within the scope of the limits of detection.

In an expedient modification of the process according to the invention,a liquor is used for colouring polytrimethylene terephthalate fibreswhich has between 3.0 and 7.0 g of disperse colorant per kg of PTMTfires being coloured. In a particularly advantageous version of theprocess, the liquor used contains between 4.5 and 5.5 g of dispersecolorant per kg of PTMT fibres. Each of the amounts of disperse colorantmentioned are given with respect to the pure colorant contained in thecommercial colorant. Commercial colorants may, as is well known, containlarge amounts of auxiliary substances (up to 80 wt. %).

As already specified, the colouring procedure according to the inventionis performed without a carrier and without the application of pressure,at the boiling point of the aqueous liquor or at lower temperatures.Depending on the composition of the aqueous liquor, in particular theamount of colorant or auxiliary colouring agent (not a carrier), theboiling point of the liquor may also be above 100° C. However, it hasbeen clearly demonstrated that even at boiling points above 100° C. thecolouring process can be performed without the application of pressure,i.e. without the use of a special pressurised vessel, for example in asealed colouring tank. In general, however, the boiling point of acolouring liquor is only slightly altered by adding the colorant and/orauxiliary agents. In an advantageous embodiment of the invention, thePTMT fibres are therefore treated at a colouring temperature betweenabout 80° and about 110° C. The treatment temperatures are in particularbetween 90° and 100° C.

In the colouring process according to the invention, an outstandinglyuniform distribution of colorant in the fibres is achieved. The colorantpenetrates very rapidly in particular into the interior of the fibres.The disperse colorants penetrate to at least a relative depth of 5% intothe fibres, with respect to the diameter of the fibres being coloured.The fibres are particularly advantageously completely coloured under thecolouring conditions according to the invention, in contrast topolyethylene terephthalate fibres which in comparison are only colouredin an annular manner under identical colouring conditions.

Coloured PTMT fibres obtainable by the colouring process according tothe invention can be used in many different ways. Basically, they can beused in all sectors in which known coloured polyester fibres havehitherto also been used. Coloured PTMT fibres obtainable by the processaccording to the invention are preferably used for the production ofwoven or knitted fabrics. Due to the exceptional mechanical propertiesof the coloured PTMT fibres, in particular their high elasticity andability to recover their shape, use in textiles which are subjected to ahigh degree of strain or as highly elastic fabrics is also preferred.

BRIEF DESCRIPTION OF THE FIGURES

The invention is explained in more detail in the following by makingreference to the enclosed figures by way of examples. The figures showthe following:

FIG. 1: An example showing the change in temperature and pressure duringthe synthesis of polytrimethylene terephthalate.

FIG. 2: For colorant C.I. Disperse Blue 139, the variation in absorptionof colorant with colouring temperature for polytrimethylene andpolyethylene terephthalate fibres.

FIG. 3: For colorant C.I. Disperse Red 60, the variation in absorptionof colorant with colouring temperature for polytrimethylene andpolyethylene terephthalate fibres.

FIG. 4: Coloured samples of PTMT and PET fibre polymers for the samecolouring time using C.I. Disperse Blue 139 as a function of thecolouring temperature, represented by shades of grey.

FIG. 5: Coloured samples of PTMT and PET fibre polymers for the samecolouring time using C.I. Disperse Red 60 as a function of the colouringtemperature, represented by shades of grey.

FIG. 6: Cross-section of fibres which have been coloured at 95° C. withC.I. Disperse Blue 139; polytrimethylene terephthalate (left-hand side)and polyethylene terephthalate (right-hand side).

FIG. 7: Cross-section of fibres which have been coloured at 120° C. withC.I. Disperse Blue 139; polytrimethylene terephthalate (left-hand side)and polyethylene terephthalate (right-hand side).

FIG. 8: Variation in the depth of penetration of colorant C.I. DisperseBlue 139 with colouring temperature for polytrimethylene andpolyethylene terephthalate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS PREPARING THE POLYMER

Polytrimethylene terephthalate was prepared in polycondensation plantswith 2 or 20 dm³ capacity.

    ______________________________________                                        Batch:                                                                        ______________________________________                                        dimethyl terephthalate                                                                            45      mol    8739 g                                     (fibre grade from Huls)                                                       1,3-propanediol     10.125  mol    7705 g                                     (Degussa AG)                                                                  titanium tetrabutylate                                                                            27      mmol   9.19 g                                     (B. pt. 155° C. at 0.015 torr)                                         n-butanol                   83.7   g                                          (B. pt. 117° C., water content < 0.01%).                               ______________________________________                                    

The batch size was 45 moles with respect to the dimethyl terephthalateused, the ratio of 1,3-propanediol (diol batch D with a 1,3-propanediolcontent of 99.96%, 0.011% of 3-hydroxymethyltetrahydropyrane, 0.005% of2-hydroxyethyl-1,3-dioxane, 0.02% of carbonyls and 0.04% of water) todimethyl terephthalate is selected to be 1:2.25 and titaniumtetrabutylate is used as a 10 wt. % strength catalyst solution inn-butanol at a concentration of 600 ppm with respect to dimethylterephthalate.

Transesterification:

Dimethyl terephthalate, 1,3-propanediol and the catalyst solution areplaced in the polycondensation apparatus and heated to 140° C. under acontinuous gentle stream of nitrogen. After the dimethyl terephthalatehas melted, the stirrer is switched on and the temperature raised to220° C. The methanol released during transesterification is distilledoff until the calculated amount has almost been reached.

Polycondensation:

The pressure in the polycondensation apparatus is lowered stepwise andthe 1,3-propanediol used in excess and 1,3-propanediol formed duringcondensation distilled off. The temperature is slowly raised to 270° C.and the pressure is again reduced until finally an oil pump vacuum(p≦0.05 bar) is reached. Polycondensation has terminated when the rateof collection of drops of 1,3-propanediol has fallen to less than 0.5drops per minute. This data applies to the 2 dm³ polycondensation plant.The energy consumed by the stirrer motor was taken as an indirectmeasure of continuing condensation in the 2 dm³ plant. In the 20 dm³plant, the torque was taken as a measure of continuing polycondensation.The vacuum in the polycondenstion apparatus was released and the finalpolytrimethylene terephthalate was discharged into a water bath under anexcess pressure of nitrogen using a gear pump, drawn out using atake-off unit and immediately granulated.

Reproducible changes in temperature during synthesis are ensured bymeans of a computer-controlled temperature programme. The otherconditions, such as pressure and stirrer speed are altered manuallyusing a fixed time programme.

The end of polycondensation was determined in preliminary experiments bymeans of the increase in torque on the stirrer shaft. The torqueincreases with increasing molecular weight and passes through a maximumwhich depends on the temperature. After passing through the maximum, thetorque drops again because then the degradation reaction proceeds morerapidly than the chain-building reaction. The optimal condensation timefor a particular temperature is determined and is then kept constant insubsequent trials.

A temperature drop can be seen at a reaction time of about 210 minuteson FIG. 1. The reason for this is the rapid distillation of largeamounts of 1,3-propanediol, wherein more energy is extracted from thereaction mixture than can be supplied to it from outside by the heater.

Furthermore, it is worth noting that the end temperature given for thepolycondensation apparatus is 240° C. This temperature is achieved 75minutes before the end of polycondensation and is then held constant upto the end of polycondensation. However, as can be seen from FIG. 1, thetemperature of the melt continuously increases further to 267° C. up tothe end of polycondensation. The heat required for this is not suppliedfrom outside by the heater, but is produced by the stirred heat in theapparatus itself. That this effect only occurs towards the end ofpolycondensation is explained by the constantly increasing viscosity ofthe polycondensation melt.

A set of polymers are produced in the way described. The most importantproperties of the polymers used in the subsequent spinning tests aregiven in Table 1.

                  TABLE 1                                                         ______________________________________                                                   Mw       COOH                                                      Polymer batch                                                                            (g/mol)   mg equ./kg!                                                                            L*    a*   b*                                   ______________________________________                                        A)  PTMT 20/14 49700    34      69    -1.8 +6.7                                   PTMT 20/11 50400    35      69    -1.6 +7.4                                   PTMT 20/13 51000    27      70    -1.5 +5.8                               B)  PTMT 20/12 53100    29      70    -1.7 +6.2                                   PTMT 20/18 55200    24      69    -1.7 +5.7                                   PTMT 20/19 55900    26      69    -1.6 +5.9                               C)  PTMT 20/15 57300    26      70    -1.8 +6.4                                   PTMT 20/16 59400    25      70    -1.7 +5.6                                   PTMT 20/17 60100    25      69    -1.7 +5.3                                   PET Rhodia                                                                Standard:       34        matted granulate                                    Mn = 20500                                                                    ______________________________________                                    

The analytical data in Table 1 were obtained as follows:

Molecular weight (Mw (g/mol)):

The weight average of the molecular weight is determined using staticlight scattering. For this, polymer solutions with the concentrations 2,4, 6, 8 and 10 g/l are prepared in 1,1,1,3,3,3-hexafluoroisopropanol.The filtered solutions at 20° C. are placed in the beam path of a heliumlaser (λ=633 nm) and the variation in intensity of the scattered lightwith angle of observation is determined. Toluene is used as a standardfor determining the optical constants and for controlling thetemperature of the samples. The scattered light intensities are plottedagainst angle and concentration on a Zimm plot.

An instrument from the Societe française d'instruments de controle etd'analyses: Photogonio/scatterometer from Wippler & Scheibling was used.

The refractive index was determined using a Wyatt Opilab 903Interferometric Refractomer from Wyatt Technology Corporation.

Terminal carboxyl groups (COOH mg equ./kg!):

The terminal carboxyl groups are determined by dissolving 4 g of polymerat 80° C. in 70 ml of a solvent mixture consisting ofphenol/chloroform=1:1 (g/g). After cooling to room temperature, 5 ml ofbenzyl alcohol and 1 ml of water are added and the solution isconductometrically titrated with 0.02N potassium hydroxide solution inbenzyl alcohol. The potassium hydroxide solution is added continuouslyusing a Dosimat 665 from Methrom and the conductivity is followed usinga DIGI 610 from WTW to which a conductivity measuring cell is attached(cell constant: 0.572).

Colour measurement (L*, a* and b*):

The ability of the polymers to be coloured is quoted using CIELAB colourvalues. The polymer granules are measured with a Minolta CR 310, whosesectral (sic) sensitivity is closely adjusted to the CIE 2° standardobserver function. The measuring field diameter is 5 cm and calibrationmakes use of a white standard.

PRODUCING THE FIBRES Drying

The polymers are dried before the spinning trials in batches of about 25kg each in a tumble dryer with a capacity of 100 dm³ from HenkhausApparatebau. Polymer batches PTMT 20/14+PTMT 20/11+PTMT 20/13, PTMT20/12+PTMT 20/18+PTMT 20/19 and PTMT 20/15+PTMT 20/16+PTMT 20/17 weremixed in order to obtain mixed batches A), B) and C) (see Table 1).

Table 2 gives the drying conditions:

                  TABLE 2                                                         ______________________________________                                         1 hour       80° C.  130° C.!                                                           p < 0.2 mbar                                          1 hour      100° C.  130° C.!                                                           p < 0.2 mbar                                         10 hours     165° C.  180° C.!                                                           p < 0.2 mbar                                         ______________________________________                                    

The temperatures given in square brackets refer to the drying ofpolyethylene terephthalate, which was processed to give fibres undersimilar conditions to those used for polytrimethylene terephthalate.

Finally the tumble dryer was cooled to room temperature while nitrogenwas introduced over the course of 12 hours.

The water content of the dried polymers was less than 0.0025% so that asignificant degree of polymer degradation during the melt spinningprocess is excluded.

Melt spinning:

A spinning unit described in T. C. Barth "Struktur und Eigenschaften vonFasern aus Polyethylen-/polybutylenterephthalat-Mischungen hergestelltim Schnellspinnverfahren", Dissertation, 1989, Univ. Stuttgart, is usedfor the spinning trials.

Spinning Unit:

Extrusion screw: 30 mm; 25 D

Spinning nozzles: 32×0.20 mm (32×0.35 mm)

Spinning pump: 2.4 cm³ /rev

Spinning temperature 250° C. 290° C.!

Reeling speed: 2000 to 5000 m/min

An aqueous emulsion made from 10% Limanol PVK and 1.6% Ukanol R is usedas a preparation. The preparation is applied at a rate of about 0.5%.

To prepare specific spinning titres, the density of the polymer meltmust be known. Accordingly, the following applies to a specificapplication of preparation:

Polytrimethylene terephthalate: ρ 250° C.=1.09 g/cm³

Polyethylene terephthalate: ρ 290° C.=1.29 g/cm³

Preparation solution: ρ 20° C.=0.923 g/cm³

During the spinning trials, commercially available polyethyleneterephthalate was spun as well as polytrimethylene terephthalate. Thespinning speeds are varied in the range 2000 to 5000 m/min for aspinning titre of 16 tex for 32 individual filaments. The spinning titreis varied in the range 9.6 to 22.4 tex for 32 individual filaments eachtime at a constant spinning speed of 3500 m/min. This corresponds to afineness of 0.3 to 0.7 tex per individual filament.

In the case of polytrimethylene terephthalate, the spinning temperatureis varied between 240° and 270° C., wherein the best results areproduced at 250° C. In addition, different spinning nozzles with nozzleorifice diameters of 200 to 350 μm are used for polytrimethyleneterephthalate. The best results are produced with a 200 μm nozzle.

The spun fibres obtained are stretched on a stretching system from DiensApparatebau. The stretching factors are selected so that the stretchedfibres have an extension of about 25%.

The mechanical properties of the spun fibres and the stretched fibresmade from polytrimethylene and polyethylene terephthalate are listed inthe following:

Polytrimethylene terephthalate spun fibres:

    ______________________________________                                                          Maximum                                                     Spinning Spinning tensile    Initial                                          speed    titre    force      modulus                                                                              Extension                                  m/min!   tex!     CN/dtex!   CN/dtex!                                                                            %                                         ______________________________________                                        2000     15.9     1.68       19.9   139                                       2500     16.1     1.97       20.8   107                                       3000     16.1     2.25       22.0   85                                        3500     16.1     2.48       23.2   68                                        4000     16.3     2.59       23.6   60                                        4500     16.3     2.53       23.3   59                                        5000     15.8     2.59       22.9   55                                        3500      9.6     2.54       23.2   68                                        3500     12.9     2.49       23.0   68                                        3500     16.1     2.48       23.2   68                                        3500     19.4     2.44       22.7   67                                        3500     22.7     2.34       22.4   64                                        ______________________________________                                    

Stretched polytrimethylene terephthalate fibres

    ______________________________________                                                                Maximum                                               Spinning        Stretch tensile                                               speed  Stretch  titre   force   Modulus                                                                              Extension                               m/min!                                                                              factor    tex!    CN/dtex!                                                                              CN/dtex!                                                                            %                                      ______________________________________                                        2000   1.78     9.0     2.76    24.1   42                                     2000   1.90     8.8     2.92    24.3   38                                     2000   2.00     8.4     2.97    24.8   32                                     2000   2.11     7.9     3.20    26.2   26                                     2000   2.20     7.9     3.34    24.6   24                                     2000   2.32     7.2     3.75    26.8   22                                     2000   2.41     7.1     3.98    27.1   20                                     2000   2.16     7.9     3.26    24.7   26                                     2500   1.87     9.2     3.43    25.1   26                                     3000   1.66     10.4    3.52    25.3   24                                     3500   1.44     12.1    3.29    25.5   25                                     4000   1.37     12.8    3.38    25.4   26                                     4500   1.36     12.8    3.34    25.1   25                                     5000   1.35     13.1    3.35    25.4   27                                     3500   1.44     7.1     3.49    25.8   24                                     3500   1.44     9.6     3.41    25.8   25                                     3500   1.44     12.1    3.29    25.5   25                                     3500   1.44     14.5    3.29    26.0   24                                     3500   1.44     16.8    3.24    24.4   22                                     ______________________________________                                    

Polyethylene terephthalate spun fibres:

    ______________________________________                                                          Maximum                                                     Spinning Spinning tensile    Initial                                          speed    titre    force      modulus                                                                              Extension                                  m/min!   tex!     CN/dtex!   CN/dtex!                                                                            %                                         ______________________________________                                        2000     15.8     1.82       21.3   156                                       2500     15.8     2.07       23.5   131                                       3000     15.3     2.29       27.1   110                                       3500     15.9     2.55       33.3   93                                        4000     15.9     2.67       41.2   79                                        4500     15.6     2.86       51.4   68                                        5000     14.8     3.21       60.2   60                                        3500      9.6     2.63       40.6   89                                        3500     12.8     2.56       37.2   90                                        3500     15.9     2.55       33.3   93                                        3500     19.0     2.54       32.9   93                                        3500     22.2     2.46       31.4   93                                        ______________________________________                                    

Stretched polyethylene terephthalate fibres:

    ______________________________________                                                                Maximum                                               Spinning        Stretch tensile                                               speed  Stretch  titre   force   Modulus                                                                              Extension                               m/min!                                                                              factor    tex!    CN/dtex!                                                                              CN/dtex!                                                                            %                                      ______________________________________                                        2000   1.79     8.9     3.45     68.1  43                                     2000   1.88     8.5     3.75     76.7  38                                     2000   1.98     8.1     3.93     82.8  31                                     2000   2.08     7.8     4.01     91.5  24                                     2000   2.20     7.4     4.26    104.0  17                                     2000   2.29     7.1     4.50    108.7   9                                     2000   2.42     6.8     5.25    117.2   6                                     2000   2.07     7.8     4.10     97.5  24                                     2500   1.85     8.7     4.08    100.2  25                                     3000   1.69     9.2     4.20    103.0  24                                     3500   1.55     10.5    4.21    103.3  26                                     4000   1.46     11.1    4.19    106.8  26                                     4500   1.38     11.6    4.06    105.1  25                                     5000   1.31     11.5    4.34    112.6  25                                     3500   1.55     6.4     4.26    110.5  24                                     3500   1.55     8.4     4.31    108.0  25                                     3500   1.55     10.5    4.21    103.3  26                                     3500   1.55     12.6    4.17    102.3  25                                     3500   1.55     14.6    4.15    101.8  25                                     ______________________________________                                    

COLOURING TESTS

The glass transition temperature of the polymers in aqueous medium is ofgreat importance for the colouring behaviour of synthetic fibres. D. R.Buchanan and J. P. Walters, Text. Res. J. 47 (1977), 398, define acolouring transition temperature. For this the absorption of colorant bythe synthetic fibres is determined as a function of temperature. Thetemperature at which the absorption of colorant reaches 50% of theequilibrium value is defined as the colouring transition temperature.The colouring transition temperature also depends, however, on the timeof colouring and the structure of the colorant.

Substrates:

The use of fibre flocks in colouring trials has the disadvantage thatthe fibres can become knotted and then can no longer be uniformlysurrounded by the colouring liquor. The unequal degrees of colouringthereby obtained cannot be used to determine the colorant content. Thecolouring trials are therefore performed using knitted fabrics made fromstretched fibres. To produce the knitted fabrics to give a knitted hose(diameter 10 cm), an Elba model circular knitting machine fromMachinenfabrik Lucas was used.

Knitted fabrics made from the following fibres were used in thecolouring trials:

    ______________________________________                                                 spinning Spinning          Stretch                                            speed    titre       Stretch                                                                             titre                                     Polymer   m/min!   tex!       factor                                                                               tex!                                     ______________________________________                                        PTMT     3500     16.1        1.44    12.1                                    PET      3500     19.0        1.55  126                                       ______________________________________                                    

In order for the stretch titre and thus the fibre diameter of the fibresbeing coloured to be comparable, a higher spinning titre was selecteddue to the different stretch factors of polyethylene terephthalate.

The fibres are washed after being knitted on the circular knittingmachine in order to remove the preparation applied during spinning.

Pretreatment:

To remove the spinning preparation, the knitted fabric is washed asfollows:

Washing conditions:

Apparatus: Mathis LAB Jumbo Jet with washing drum

Temperature: 30° C.

Duration: 120 min

Washing liquor: 1 g/l of Kieralon® EDB from Bayer AG

Liquor ratio: 1:50

To avoid shrinking during colouring and to improve the dimensionalstability of the knitted fabrics, these are thermofixed at 180° C. forone minute. This relaxes the stresses in the fibres produced duringstretching. The thermofixed knitted fabrics made from polytrimethyleneterephthalate exhibit a higher degree of area shrinkage than those madefrom polyethylene terephthalate.

Fixing conditions:

Apparatus: Mathis dryer

Temperature: 180° C.

Duration: 1 min

Colorant:

Two disperse colorants were selected which clearly differed with regardto their coefficients of diffusion:

    ______________________________________                                         ##STR2##                                                                     C.I. Disperse Blue 139                                                                      0.8        mono-azo colorant                                                             resolin marine blue GLS                                                       from Bayer AG                                        C.I. Disperse Red 60                                                                        3.4        anthraquinone colorant                                                        resolin red FB                                                                from Bayer AG                                        ______________________________________                                    

The extinction coefficient of the pure colorant must be known forquantitative determination of the absorption of colorant. Purificationof the disperse colorants mentioned above is described in detail in E.M. Schnaith (Dissertation 1979, Univ. of Stuttgart).

The colouring temperatures are varied in the range between 60° C. and140° C.

Colouring is always started at 40° C. and the rate of heating isselected so that the colouring temperature is reached after 45 minutes.The rate of cooling is always 1 K/min until the bath reaches atemperature of 40° C.

Colouring conditions:

Colouring equipment: Ahiba Polymat

Colouring time: 60 min

Liquor ratio: 1:20

Liquor: 1 g/l of colorant 2 g/l of Avolan®IS from Bayer AG 2 g/l ofsodium dihydrogen phosphate dihydrate

Reductive after-treatment:

To remove colorant which has been deposited on the surface of thefibres, the colouring procedure is followed by a reductiveafter-treatment. The rate of heating the reduction liquor is 2 K/min,the rate of cooling is 1 K/min.

Reduction conditions:

Equipment: Ahiba Polymat

Temperature: 70° C.

Liquor ratio: 1:20

Liquor 3 g/l of sodium dithionite 1.2 g/l of sodium hydroxide 1 g/l ofLevegal® HTN from Bayer AG

Finally, the knitted fabric is acidified with 5% strength formic acid.

Absorption of colorant:

To determine the absorption of colorant, the fibres coloured atdifferent temperatures are exhaustively extracted with chlorobenzene.The extracts are diluted to a specific volume and the extinctions of thesolution are determined using a UV/VIS spectrophotometer of the typeLambda 7 from the Perkin Elmer Bodensee works. The colorant content canbe determined from the extinction of the extraction solution at thecharacteristic wavelengths

C.I. Disperse Blue 139: 604 nm and

C.I. Disperse Red 60: 516 nm,

by using the corresponding calibration lines.

Determining the colorant content CC in g/kg of goods is performed usingthe numerical equations:

C.I. Disperse Blue 139: ##EQU1##

FIGS. 2 and 3 show the absorption of colorant by polytrimethyleneterephthalate fibres as a function of the colouring temperature ascompared with that of polyethylene terephthalate fibres.

In FIGS. 2 and 3, the horizontal line indicates the amount of colorantpresent in the colouring liquor with respect to the amount of substrateused.

It can be seen from FIG. 2 that colouring of polytrimethyleneterephthalate fibres starts at about 70° C., whereas polyethyleneterephthalate fibres are only definitely coloured at temperatures above90° C.

The maximum determinable absorption of colorant is about 95% of themaximum possible absorption of colorant because the fibre samples arereductively after-treated before extraction. This reductively destroysthe colorant adhering to the surface of the fibres and therefore lowersthe maximum determinable colorant content.

Furthermore, FIG. 2 shows that the total colorant is absorbed from thecolouring liquor onto polytrimethylene terephthalate fibres at acolouring temperature of 100° C. On the other hand, at a colouringtemperature of 100° C., only about 15% of the colorant present isabsorbed onto the polyethylene terephthalate fibres.

For the colorant present to be completely absorbed onto polyethyleneterephthalate fibres, the colouring temperature has to be raised to 130°C. This means that bath-exhaustive colouring of polyethyleneterephthalate fibres has to be performed in sealed containers underpressure (HT colouring conditions).

In the case of C.I. Disperse Red 60, a disperse colorant with a highercoefficient of diffusion, an almost identical plot of absorption ofcolorant against colouring temperature is observed as with C.I. DisperseBlue 139.

The trace of the curve, however, in the case of C.I. Disperse Red 60 isshifted by about 5 to 10K to lower temperatures than with C.I. DisperseBlue 139. This behaviour is explained by the higher coefficient ofdiffusion of C.I. Disperse Red 60, because the colorant molecules candiffuse into the interior of the fibres more rapidly.

Colouring with C.I. Disperse Red 60 shows a maximum absorption ofcolorant by polytrimethylene terephthalate fibres as from a colouringtemperature of 95° C.

With polyethylene terephthalate fibres, the maximum absorption ofcolorant is only achieved at a colouring temperature of 120° C., so thathere again bath-exhaustive colouring has to be performed in sealedequipment under pressure.

The colouring transition temperatures of polytrimethylene terephthalateand polyethylene terephthalate are therefore:

    ______________________________________                                                         PTMT  PET                                                    ______________________________________                                        C.I. Disperse Blue 139                                                                           91° C.                                                                         107° C.                                     C.I. Disperse Red 60                                                                             84° C.                                                                         100° C.                                     ______________________________________                                    

The colouring transition temperature when colouring with C.I. DisperseRed 60 is about 7K lower than when colouring with C.I. Disperse Blue 139due to its higher coefficient of diffusion. The difference of 16K in thecolouring transition temperatures of the two polymers, however, remainsconstant.

FIGS. 4 and 5 show coloured samples of the two fibre polymers for thesame colouring time as a function of colouring temperature. This bestdemonstrates the difference in absorption of colorant. The colourintensity differences are represented by shades of grey.

Distribution of colorant:

Distribution of the colorant in the fibres can be assessed usingcross-sections of the fibres. Complete colouring and annular colouringcan be differentiated. Cross-sections of fibres are obtained byembedding the fibres in an acrylate and cutting them in slices 10 μmthick with a Minot-Mikrotom from the Jung Co. The cross-sectionalabsorptions are photographed using a Zeiss Axioplan microscope. Thefastness of a colour when shear strain is placed on the coloured flatstructure is higher in the case of complete colouring than with annularcolouring, when the colorant is only incorporated into the externallayer of the fibre.

The cross-sections investigated were coloured with C.I. Disperse Blue139 because this colorant has a very low coefficient of diffusion. Whenusing other colorants with higher coefficients of diffusion, completecolouring would be expected even at low colouring temperatures.

FIGS. 6 and 7 show cross-sections of polytrimethylene and polyethyleneterephthalate fibres which have been coloured at 95° C. and 120° C. withC.I. Disperse Blue 139.

In the case of the polyethylene terephthalate fibres, the titaniumdioxide particles with which the polymer granules used have been mattedcan be seen.

The cross-sections of the fibres show that the colorant penetrates intothe interior of polytrimethylene terephthalate fibres more rapidly thanis the case with polyethylene terephthalate fibres.

FIG. 8 shows the depth of penetration with respect to the diameter ofthe fibres as a function of colouring temperature.

If FIG. 8 is compared with FIG. 2, then the following observations maybe made:

Polytrimethylene terephthalate fibres can be outstandingly coloured withC.I. Disperse Blue 139 at boiling point. The fibres absorb the entireamount of the colorant present in the colouring liquor. Theconcentration of colorant is greatest in the edge areas. During HTcolouring, the diffusion of colorant is accelerated so that uniformcomplete colouring can be observed over the whole cross-section of thefibres.

In contrast, the absorption of colorant by polyethylene terephthalatefibres is much lower at the boiling point. The absorption of colorant bythe fibres is only 10% of the colorant present in the colouring liquor.Under HT conditions, polyethylene terephthalate fibres can also beeffectively coloured. The entire amount of colorant penetrates into thefibres, but complete colouring of the fibres is not observed with C.I.Disperse Blue 139.

Further advantages and embodiments of the invention may be found in thefollowing patent claims.

We claim:
 1. A process for colouring polytrimethylene terephthalatefibres, in which the fibres are treated in an aqueous liquor containingat least one disperse colorant, in the absence of a carrier andapplication of pressure,wherein colouring begins when the liquortemperature is between 20° and 50° C., the temperature then being raisedover a period of between 20 and 90 minutes, to a maximum temperature ofbetween about 80° and 110° C., which temperature is maintained for atleast 20 minutes, the temperature then being lowered to 20° to 50° C.,so that at least 95 wt. % of the colorant present in the liquor isabsorbed by the fibres and the disperse colorant penetrates the fibresto a relative depth of at least 5% with respect to the diameter of thefibres being coloured.
 2. A process according to claim 1 wherein aliquor is used which contains between 3.0 and 7.0 g of pure dispersecolorant per kg of PTMT fires being coloured.
 3. A process according toclaim 2, wherein a liquor with a disperse colorant content of 4.5 to 5.5g of pure disperse colorant per kg of PTMT fibres is used.
 4. A processaccording to claim 1, wherein the colouring temperature is between 90°and 100° C.
 5. A process according to claim 1, wherein the colouringtemperature is between 90° and 100° C.
 6. A process according to claim1, wherein the colouring temperature is between 90° and 100° C.
 7. Aprocess according to claim 1, wherein the fibres are completelycoloured.
 8. A process according to claim 2, wherein the fibres arecompletely coloured.
 9. A process according to claim 3, wherein thefibres are completely coloured.
 10. A process according to claim 4,wherein the fibres are completely coloured.
 11. A process according toclaim 5, wherein the fibres are completely coloured.
 12. A processaccording to claim 6, wherein the fibres are completely coloured.
 13. Aprocess according to claim 1, wherein the liquor temperature is raisedover 45 minutes.
 14. A process according to claim 1, wherein colouringis continued for 30-90 minutes.
 15. A process according to claim 1,wherein the liquor temperature is lowered at a cooling rate of 1° C. perminute.
 16. A process according to claim 13, wherein colouring iscontinued for 30-90 minutes.
 17. A process according to claim 13,wherein the liquor temperature is lowered at a cooling rate of 1° C. perminute.
 18. A process according to claim 14, wherein the liquortemperature is lowered at a cooling rate of 1° C. per minute.
 19. Aprocess according to claim 1 wherein the liquor temperature is raisedover 45 minutes, the colouring is continued for 30-60 minutes, and theliquor temperature is lowered at a cooling rate of 1° C. per minute.